Parcel Recognition Device, Parcel Sorting System, and Parcel Recognition Method

1. A parcel recognition device that recognizes parcel based on a color image including one or more parcels on a conveyor, the device comprising: a processor; and a memory, wherein by cooperating with the memory, the processor estimates a region of the one or more parcels in the color image, switches a color of a background in the color image, the background being which is a region including a region of the conveyor in the color image and excluding the estimated region of the one or more parcels in the color image, and recognizes each of the one or more parcels based on the color image after the color of the background is switched.

2. The parcel recognition device of claim 1 , wherein the processor switches the color of the background for each predetermined period.

3. The parcel recognition device of claim 2 , wherein the processor changes a period for switching the color of the background, according to recognition accuracy of the parcel.

4. The parcel recognition device of claim 1 , wherein the processor sets a color different from a color of parcel successfully recognized in a past frame as a candidate of the color of the background.

5. The parcel recognition device of claim 1 , wherein the processor further receives a designation of a candidate of a color of a background, and switches the color of the background within a range of the received candidate.

6. The parcel recognition device of claim 1 , the processor estimates the region of the one or more parcels in the color image, by using a distance image.

7. A parcel sorting system comprising: a projection instruction device including the parcel recognition device according to claim 1 ; a label reader that reads parcel identification information from a label attached to the parcel; a distance image sensor that obtains a distance image including the parcel; a color image sensor that obtains a color image including the parcel; and an image projection device which projects a projection image indicating a sorting destination on parcel.

8. A parcel recognition method of recognizing parcel based on a color image including one or more parcels on a conveyor, the method comprising: by causing a processor to cooperate with a memory, estimating a region of the one or more parcels in the color image; switching a color of a background in the color image, the background being a region including a region of the conveyor in the color image and excluding the estimated region of the one or more parcels in the color image; and recognizing each of the one or more parcels based on the color image after the color of the background is switched.

9. The parcel recognition device according to claim 1 , wherein the one or more parcels including a parcel having a color similar to a color of the conveyor.

10. The parcel recognition device according to claim 3 , wherein the period is shortened when the recognition accuracy decreases.

11. The parcel recognition device according to claim 4 , wherein the processor detects the color of the parcel successfully recognized in the past frame; and the processor excludes the detected color of parcel from the candidate of the color of the background in a current frame.